// Word cloud layout by Jason Davies, http://www.jasondavies.com/word-cloud/
// Algorithm due to Jonathan Feinberg, http://static.mrfeinberg.com/bv_ch03.pdf
(function() {

    if (typeof define === "function" && define.amd) define(["d3"], cloud);
    else cloud(this.d3);

    function cloud(d3) {
        d3.layout.cloud = function cloud() {
            var size = [256, 256],
                text = cloudText,
                font = cloudFont,
                fontSize = cloudFontSize,
                fontStyle = cloudFontNormal,
                fontWeight = cloudFontNormal,
                rotate = cloudRotate,
                padding = cloudPadding,
                spiral = archimedeanSpiral,
                words = [],
                timeInterval = Infinity,
                event = d3.dispatch("word", "end"),
                timer = null,
                random = Math.random,
                cloud = {};

            cloud.start = function() {
                var board = zeroArray((size[0] >> 5) * size[1]),
                    bounds = null,
                    n = words.length,
                    i = -1,
                    tags = [],
                    data = words.map(function(d, i) {
                        d.text = text.call(this, d, i);
                        d.font = font.call(this, d, i);
                        d.style = fontStyle.call(this, d, i);
                        d.weight = fontWeight.call(this, d, i);
                        d.rotate = rotate.call(this, d, i);
                        d.size = ~~fontSize.call(this, d, i);
                        d.padding = padding.call(this, d, i);
                        return d;
                    }).sort(function(a, b) { return b.size - a.size; });

                if (timer) clearInterval(timer);
                timer = setInterval(step, 0);
                step();

                return cloud;

                function step() {
                    var start = Date.now();
                    while (Date.now() - start < timeInterval && ++i < n && timer) {
                        var d = data[i];
                        d.x = (size[0] * (random() + .5)) >> 1;
                        d.y = (size[1] * (random() + .5)) >> 1;
                        cloudSprite(d, data, i);
                        if (d.hasText && place(board, d, bounds)) {
                            tags.push(d);
                            event.word(d);
                            if (bounds) cloudBounds(bounds, d);
                            else bounds = [{x: d.x + d.x0, y: d.y + d.y0}, {x: d.x + d.x1, y: d.y + d.y1}];
                            // Temporary hack
                            d.x -= size[0] >> 1;
                            d.y -= size[1] >> 1;
                        }
                    }
                    if (i >= n) {
                        cloud.stop();
                        event.end(tags, bounds);
                    }
                }
            }

            cloud.stop = function() {
                if (timer) {
                    clearInterval(timer);
                    timer = null;
                }
                return cloud;
            };

            function place(board, tag, bounds) {
                var perimeter = [{x: 0, y: 0}, {x: size[0], y: size[1]}],
                    startX = tag.x,
                    startY = tag.y,
                    maxDelta = Math.sqrt(size[0] * size[0] + size[1] * size[1]),
                    s = spiral(size),
                    dt = random() < .5 ? 1 : -1,
                    t = -dt,
                    dxdy,
                    dx,
                    dy;

                while (dxdy = s(t += dt)) {
                    dx = ~~dxdy[0];
                    dy = ~~dxdy[1];

                    if (Math.min(Math.abs(dx), Math.abs(dy)) >= maxDelta) break;

                    tag.x = startX + dx;
                    tag.y = startY + dy;

                    if (tag.x + tag.x0 < 0 || tag.y + tag.y0 < 0 ||
                        tag.x + tag.x1 > size[0] || tag.y + tag.y1 > size[1]) continue;
                    // TODO only check for collisions within current bounds.
                    if (!bounds || !cloudCollide(tag, board, size[0])) {
                        if (!bounds || collideRects(tag, bounds)) {
                            var sprite = tag.sprite,
                                w = tag.width >> 5,
                                sw = size[0] >> 5,
                                lx = tag.x - (w << 4),
                                sx = lx & 0x7f,
                                msx = 32 - sx,
                                h = tag.y1 - tag.y0,
                                x = (tag.y + tag.y0) * sw + (lx >> 5),
                                last;
                            for (var j = 0; j < h; j++) {
                                last = 0;
                                for (var i = 0; i <= w; i++) {
                                    board[x + i] |= (last << msx) | (i < w ? (last = sprite[j * w + i]) >>> sx : 0);
                                }
                                x += sw;
                            }
                            delete tag.sprite;
                            return true;
                        }
                    }
                }
                return false;
            }

            cloud.timeInterval = function(_) {
                return arguments.length ? (timeInterval = _ == null ? Infinity : _, cloud) : timeInterval;
            };

            cloud.words = function(_) {
                return arguments.length ? (words = _, cloud) : words;
            };

            cloud.size = function(_) {
                return arguments.length ? (size = [+_[0], +_[1]], cloud) : size;
            };

            cloud.font = function(_) {
                return arguments.length ? (font = d3.functor(_), cloud) : font;
            };

            cloud.fontStyle = function(_) {
                return arguments.length ? (fontStyle = d3.functor(_), cloud) : fontStyle;
            };

            cloud.fontWeight = function(_) {
                return arguments.length ? (fontWeight = d3.functor(_), cloud) : fontWeight;
            };

            cloud.rotate = function(_) {
                return arguments.length ? (rotate = d3.functor(_), cloud) : rotate;
            };

            cloud.text = function(_) {
                return arguments.length ? (text = d3.functor(_), cloud) : text;
            };

            cloud.spiral = function(_) {
                return arguments.length ? (spiral = spirals[_] || _, cloud) : spiral;
            };

            cloud.fontSize = function(_) {
                return arguments.length ? (fontSize = d3.functor(_), cloud) : fontSize;
            };

            cloud.padding = function(_) {
                return arguments.length ? (padding = d3.functor(_), cloud) : padding;
            };

            cloud.random = function(_) {
                return arguments.length ? (random = _, cloud) : random;
            };

            return d3.rebind(cloud, event, "on");
        };

        function cloudText(d) {
            return d.text;
        }

        function cloudFont() {
            return "serif";
        }

        function cloudFontNormal() {
            return "normal";
        }

        function cloudFontSize(d) {
            return Math.sqrt(d.value);
        }

        function cloudRotate() {
            return (~~(Math.random() * 6) - 3) * 30;
        }

        function cloudPadding() {
            return 1;
        }

        // Fetches a monochrome sprite bitmap for the specified text.
        // Load in batches for speed.
        function cloudSprite(d, data, di) {
            if (d.sprite) return;
            c.clearRect(0, 0, (cw << 5) / ratio, ch / ratio);
            var x = 0,
                y = 0,
                maxh = 0,
                n = data.length;
            --di;
            while (++di < n) {
                d = data[di];
                c.save();
                c.font = d.style + " " + d.weight + " " + ~~((d.size + 1) / ratio) + "px " + d.font;
                var w = c.measureText(d.text + "m").width * ratio,
                    h = d.size << 1;
                if (d.rotate) {
                    var sr = Math.sin(d.rotate * cloudRadians),
                        cr = Math.cos(d.rotate * cloudRadians),
                        wcr = w * cr,
                        wsr = w * sr,
                        hcr = h * cr,
                        hsr = h * sr;
                    w = (Math.max(Math.abs(wcr + hsr), Math.abs(wcr - hsr)) + 0x1f) >> 5 << 5;
                    h = ~~Math.max(Math.abs(wsr + hcr), Math.abs(wsr - hcr));
                } else {
                    w = (w + 0x1f) >> 5 << 5;
                }
                if (h > maxh) maxh = h;
                if (x + w >= (cw << 5)) {
                    x = 0;
                    y += maxh;
                    maxh = 0;
                }
                if (y + h >= ch) break;
                c.translate((x + (w >> 1)) / ratio, (y + (h >> 1)) / ratio);
                if (d.rotate) c.rotate(d.rotate * cloudRadians);
                c.fillText(d.text, 0, 0);
                if (d.padding) c.lineWidth = 2 * d.padding, c.strokeText(d.text, 0, 0);
                c.restore();
                d.width = w;
                d.height = h;
                d.xoff = x;
                d.yoff = y;
                d.x1 = w >> 1;
                d.y1 = h >> 1;
                d.x0 = -d.x1;
                d.y0 = -d.y1;
                d.hasText = true;
                x += w;
            }
            var pixels = c.getImageData(0, 0, (cw << 5) / ratio, ch / ratio).data,
                sprite = [];
            while (--di >= 0) {
                d = data[di];
                if (!d.hasText) continue;
                var w = d.width,
                    w32 = w >> 5,
                    h = d.y1 - d.y0;
                // Zero the buffer
                for (var i = 0; i < h * w32; i++) sprite[i] = 0;
                x = d.xoff;
                if (x == null) return;
                y = d.yoff;
                var seen = 0,
                    seenRow = -1;
                for (var j = 0; j < h; j++) {
                    for (var i = 0; i < w; i++) {
                        var k = w32 * j + (i >> 5),
                            m = pixels[((y + j) * (cw << 5) + (x + i)) << 2] ? 1 << (31 - (i % 32)) : 0;
                        sprite[k] |= m;
                        seen |= m;
                    }
                    if (seen) seenRow = j;
                    else {
                        d.y0++;
                        h--;
                        j--;
                        y++;
                    }
                }
                d.y1 = d.y0 + seenRow;
                d.sprite = sprite.slice(0, (d.y1 - d.y0) * w32);
            }
        }

        // Use mask-based collision detection.
        function cloudCollide(tag, board, sw) {
            sw >>= 5;
            var sprite = tag.sprite,
                w = tag.width >> 5,
                lx = tag.x - (w << 4),
                sx = lx & 0x7f,
                msx = 32 - sx,
                h = tag.y1 - tag.y0,
                x = (tag.y + tag.y0) * sw + (lx >> 5),
                last;
            for (var j = 0; j < h; j++) {
                last = 0;
                for (var i = 0; i <= w; i++) {
                    if (((last << msx) | (i < w ? (last = sprite[j * w + i]) >>> sx : 0))
                        & board[x + i]) return true;
                }
                x += sw;
            }
            return false;
        }

        function cloudBounds(bounds, d) {
            var b0 = bounds[0],
                b1 = bounds[1];
            if (d.x + d.x0 < b0.x) b0.x = d.x + d.x0;
            if (d.y + d.y0 < b0.y) b0.y = d.y + d.y0;
            if (d.x + d.x1 > b1.x) b1.x = d.x + d.x1;
            if (d.y + d.y1 > b1.y) b1.y = d.y + d.y1;
        }

        function collideRects(a, b) {
            return a.x + a.x1 > b[0].x && a.x + a.x0 < b[1].x && a.y + a.y1 > b[0].y && a.y + a.y0 < b[1].y;
        }

        function archimedeanSpiral(size) {
            var e = size[0] / size[1];
            return function(t) {
                return [e * (t *= .1) * Math.cos(t), t * Math.sin(t)];
            };
        }

        function rectangularSpiral(size) {
            var dy = 4,
                dx = dy * size[0] / size[1],
                x = 0,
                y = 0;
            return function(t) {
                var sign = t < 0 ? -1 : 1;
                // See triangular numbers: T_n = n * (n + 1) / 2.
                switch ((Math.sqrt(1 + 4 * sign * t) - sign) & 3) {
                    case 0:  x += dx; break;
                    case 1:  y += dy; break;
                    case 2:  x -= dx; break;
                    default: y -= dy; break;
                }
                return [x, y];
            };
        }

        // TODO reuse arrays?
        function zeroArray(n) {
            var a = [],
                i = -1;
            while (++i < n) a[i] = 0;
            return a;
        }

        var cloudRadians = Math.PI / 180,
            cw = 1 << 11 >> 5,
            ch = 1 << 11,
            canvas,
            ratio = 1;

        if (typeof document !== "undefined") {
            canvas = document.createElement("canvas");
            canvas.width = 1;
            canvas.height = 1;
            ratio = Math.sqrt(canvas.getContext("2d").getImageData(0, 0, 1, 1).data.length >> 2);
            canvas.width = (cw << 5) / ratio;
            canvas.height = ch / ratio;
        } else {
            // Attempt to use node-canvas.
            canvas = new Canvas(cw << 5, ch);
        }

        var c = canvas.getContext("2d"),
            spirals = {
                archimedean: archimedeanSpiral,
                rectangular: rectangularSpiral
            };
        c.fillStyle = c.strokeStyle = "red";
        c.textAlign = "center";
    }

})();